acad3=# EXPLAIN SELECT  book_id FROM mod_lib_book_foreword_index WHERE book_foreword LIKE 'прав%';
                                  QUERY PLAN
------------------------------------------------------------------------------
 Seq Scan on mod_lib_book_foreword_index  (cost= 0 . 00 .. 3012 . 99  rows= 1  width= 8 )
   Filter: ((book_foreword)::text ~~ 'прав%'::text)
( 2  rows)

Time:  15 . 000  ms
acad3=# EXPLAIN SELECT  book_id FROM mod_lib_book_foreword_index WHERE book_foreword = 'прав';
                                     QUERY PLAN
-------------------------------------------------------------------------------------
 Bitmap Heap Scan on mod_lib_book_foreword_index  (cost= 4 . 41 .. 63 . 01  rows= 16  width= 8 )
   Recheck Cond: ((book_foreword)::text = 'прав'::text)
   ->  Bitmap Index Scan on idx_book_foreword  (cost= 0 . 00 .. 4 . 41  rows= 16  width= 0 )
         Index Cond: ((book_foreword)::text = 'прав'::text)
( 4  rows)

Time:  0 . 000  ms

acad3=# EXPLAIN SELECT  book_id FROM mod_lib_book_foreword_index WHERE book_foreword LIKE 'прав%';
                                                            QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------------
 Index Scan using idx_book_foreword on mod_lib_book_foreword_index  (cost= 0 . 00 .. 8 . 29  rows= 1  width= 8 )
   Index Cond: (((book_foreword)::text ~>=~ 'прав'::character varying) AND ((book_foreword)::text ~<~ 'праг'::character varying))
   Filter: ((book_foreword)::text ~~ 'прав%'::text)
( 3  rows)

Time:  0 . 000  ms